Tuning control



Feb. 2, 1937. P. J. scHwARzHAUPT TUNING CONTROL Filed NOV. 21, 1935 Iventorf: Paul J. ohwarzhauph b ya AJM ld [Vit-[Kiss Attortnel.;

Patented Feb. 2, 1937 UNITED STATES PATENT OFFICE General Electric Company, a

New York corporation o! Application November 21, 1935, Serial No. 50,908

2 Claims.

My invention relates to tuning control mechanisms for radio transmitting or receiving systems.

In certain types of radio equipment, it is desirable to provide positioning devices for the tuning control element, which positioning devices correspond respectively to certain predetermined desired frequency settings of the control element. 'I'hese devices enable the operator rapidly and quickly to turn from one predetermined frequency setting of the control element to another. The usual type of positioning device, due to the inherent nature of its structure, is incapable of adjustment for different frequencies spread apart on the indicating dial.of the system by but a few degrees. It is an object of my invention to provide an improved tuning device which will permit rapid and accurate change from one predetermined tuning position to another irrespective of how close together any two desired frequencies may be.

In accordance with my invention a positioning plate or ring having a plurality of notches on one of its outer faces is mounted on the tuning control shaft of a radio transmitting or receiving system. A plurality of positioning devices, assembled on a single concentric stationary track located about the positioning plate, are provided with spring pressed balls or plungers which ride on the notched face of the positioning plate. As the positioning plate rotates with movement of the control shaft, the spring pressed balls will from time to time fall into one of the notches and tend to prevent further rotation. Since this tendency to prevent further rotation is readily felt by the operator as he turns the control shaft, it is apparent that by properly positioning a positioning device on the concentric track and by allocating one of the notches to that particular device, a simple indication of a desired tuning position is attained. Furthermore, since a separate notch is provided for each positioning device, there is no limitation as to how close together two desired frequencies may be for one spring pressed ball may be just riding out of its corresponding notch as a second spring pressed'ball falls into its corresponding notch.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof may best be understood by reference to the following description taken in connection with the accompanying drawing in which Fig. 1 is an end view partly in cross section and Fig. 2 is a plan view of one embodiment of my invention.

Referring to Fig. 1 of the drawing, I have indicated at I a tuning element or control shaft o! 5 the apparatus to which my invention is applied. This control shaft I is carried by front panel 2 of the apparatus to be controlled and has secured thereon a transparent disc 3 by means of a nut 25 -and a plurality of pins 26. Secured to the front face of panel 2 and in proximity to the transparent disc 3 is a photo-etched plate 4 which has the usual markings thereon for indicating frequency, which markings are, of course, visible through the disc 3. Riveted or otherwise securejil to disc 3 is a positioning plate 5 which has a plurality of notches therein for purposes presently to be indicated. Circumferentially disposed about positioning plate 5 is a track I2 having a dove-tail cross section, which track may be secured to the panel in any suitable way. Movably mounted on track I2 are a plurality of positioning devices I4,

I1, I8, and I9, each of which comprises a block 20, and L-piate 2 I, a spring 22, a set-screw 23, and

a plunger 24, all of which are clearly illustrated in connection with the positioning device I4. Block 20 and L-plate 2| have such a cross section that the positioning devices are held to the track I2 but which permits the positioning devices to be moved along track I2 when the set-screw 23 is 30 loosened. Plunger pins 24 ride on the front face of positioning plate 5 and due to the pressure exerted by the spring 22, fall into notches in this plate.

Fig. 2 represents a plan view of the apparatus. 35 This ligure shows the plate 5 in the form of an annulus about the periphery of disc 3 and having notches 6, 1, 0, 9, I0 and II at desired intervals about the annulus. Also about the annulus 5 is the track I2, secured to plate 2 by screws I3, car- 40 rying the positioning devices I4, I5, I6, I1, I8 and I9, each containing a plunger member 24, referred to in connection with Fig. 1, which cooperate with notches 6, 1, 8, 9, I0 and I I in the positioning plate 5 thereby to secure the said plate 45 and, hence, the control shaft I in desired positions.

One notch and one positioning device is necessary for each desired frequency setting of the tuning control. Consequently, each positioning device is given an individual mark such as diierent letters of the alphabet and a similar mark indicates the cooperating notch of the positioning plate. For example, positioning device I4 is lettered A and notch 6 is also lettered A; positioning device I5 and notch 1 are lettered B; 55

positioning device Il and notch l are lettered C, etc.

'Ihe operation of my invention is as follows: 'I'he control device is first adjusted by rotating shaft I until plunger 24 of positioning device I4 falls into notch 8. Set-screw 23 of device I4 is then loosened and shaft I is rotated until the radio system is adjusted for operation at a desired frequency. Set-screw 23 is then tightened. Positioning devices I6, I6, I1, I8 and I8 are similarly adjusted at positions corresponding to other frequencies at which the system is adapted to operate.

Assuming now that control shaft I is in such a position that plunger pin 24 of device I4 rests in notch 8 and it is desired to change the frequency of operation to one corresponding to the position of device I5, the operator causes the control shaft I to be rotated until plunger pin 24 of device I5 falls into its cooperating notch 1. The system is now adjusted for'operation at a second desired frequency. If it is then desired to change to some third predetermined frequency as, for example, that corresponding to positioning device E, the operator merely causes control shaft I to be rotated until the plunger 24 of positioning device lettered E falls into its co operating notch lettered E.

It is obvious that the number of positioning devices and cooperating notches correspond to the number of desired frequencies at which the radio system operates. It is also apparent that there is no limitation as to how close together any two desired frequencies may be for, due to the provision of a plurality of notches on the positioning plate, the plunger pin 24 on device I4, for example, may be just riding out of its corresponding notch 8 as the plunger pin 24 aocaesrr on device Il, for example, falls into its corre-7 spending notch l. Thus the notches and I may correspond to frequencies closely spaced upon the seal of disc 4. n

While I have shown a particular embodiment oi my invention it will, of course, be understood that I do not wish to be limited thereto since dierent modiilcations may be made and I, therefore, contemplate by the appended claims to cover all such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a tuning device, the combination comprising a stationary member, a control shaft supported thereby, a track concentric to said shaft mounted on said stationary member, a plurality of positioning devices 'movably mounted on said track, a positioning plate having a plurality of notches circumferentially located on one face thereof mounted on said shaft, means for locking said positioning devices at predetermined positions on said track and spring biased means bn each of said positioning devices for registering with one of said notches at different angular positions of said shaft.

2. In a tuning device, the combination coniprising a stationary member, a control shaft supported thereby, a ring having a plurality of notches on one face thereof rigidly mounted on said shaft, a second concentric ring secured to said stationary member, and a plurality of spring-pressed elements adjustably mounted on said second ring and adapted to'register with said notches at a plurality of different predetermined angular positions of said shaft.

PAUL SCHWARZHAUPT. 

